2 Live Databases

scenario 1
can there be 2 live databases pointed to one front end application, at 2 different locations (databases), maybe one within the LAN, and the other at a greater locaiton with the courtesy of the VPN
assumption - network domain is the same

scenario 2
can there be 2 live databases pointed to one front end application, at 2 different locations (databases), maybe one within the LAN, and the other at a greater locaiton with the courtesy of the VPN
assumption - network domain different

If application and 2 DBs are in same domain, you can use windows authentication to connect the database (2 seperate connection string).
if application has to connect a DB server in different domain, you have to use SQL login.

For distributed trnsactions, you have to use MSDTC (Component Services)

You can also create a linked server on DB1 that points to DB2 server with appropriate MSDTC permission settings on both the DB servers and your application can perform transactions on both the DB server using one connection string